US2053961A - Circuit breaker mechanism - Google Patents

Description

Sept. 8, I936. L. J. LINDE v CIRCUIT BREAKER MECHANISM Original Filed Oct. 19, 1933 2 Sheeis-Sheet 1 Inventor Leonard J. Linde H|s A Lorne qp 1936- L. J. LINDE CIRCUIT BREAKER MECHANISM Original Filed Oct. 19, 1933 2 Sheets-Sheet 2 Fig. 0.

U 5 fimmH 4 8 n- 4 N. I. a r. a rJ 1 6 N wa 4.3 F f i O y o W 4/ Q a o :M w 5 U i Inventor Leonard J- Linde,

b5 H is Attorney;-

Patente Sept. i936 PATEN omorlrr BREAKER Ii/iECfi'bliiI Leonard 3. Kinds, Felon-oft, We, assignor to (General Electric Company, a corporation oi New York My invention relates to circuit breaker mechanisms, more particularly to mechanisms of the trip-free type wherein a collapsible thrust-transmitting structure for effecting the circuit closing 5 operation is controlled during the entire closing operation by tripping means, and has for its principal object the provision of an improved circuit breaker mechanism which shall be efficient and reliable in operation, simple and compact in design while permitting ready assembly or disassembly of the component parts, and rugged in construction.

This application is a division of mycopending application Serial No. 694,282, filed October 19, 1933, for Operating mechanism now Patent No. 2,034,145 issued March 17, 1936.

My invention will be more fully set forth in the following description referring to the accompanying drawings, and the features of/ novelty which characterize my invention will be pointed andforming a part of this specification.

Referring to the drawings, Fig. l is a perspective view partly in section illustrating in detail an electric air circuit breaker and its associated operating mechanism embodying the present invention; Fig. 2 is a view, partly in section, of brake structure illustrated in Fig. 1 in the braking position thereof; Fig. 3 is a similar view of the brake structure in non-braking position; Fig. 4-is an elevational view of apparatus illustrated in Fig. 1 in the closed circuit position; Fig. 5 is a similar view illustrating the apparatus in open circuit position before the resetting operation is completed; Fig. 6 is a similar view of the apparatus illustrating the same in the completely reset position; Fig. 7 is an elevational front view of the assembled circuit breaker and operating mechanism unit; Fig. 8 is an elevational side view of 4 the unit shown in Fig. '7, and Fig. 9 is a detailed view of a modified form of the resetting means. Referring more particularly to Fig. 1, there is illustrated operating mechanism I for effecting predetermined travel of the movable element of 45 an electric circuit breaker 2. The operating mechanism I generally comprises suitable motive means as an electric motor 3 and collapsible thrust transmitting means 4 which is operatively connected to the motor in a manner hereinafter described. The'thrust transmitting structure 4 element 5 of the circuit breaker.

The circuit breaker as shown is of the polyphase type, the circuitgcontrolling contacts of each phase 55 including (Figs. 1 and 5) movable arcing and out with particularity in the claims annexed to is likewise operatively connected tothe movable pairs of movable and stationary contacts 68 and l9, a magnetic blowout coil l2 and terminal I 3. There are likewise included a pair of transfer or burning" contacts 'I' and 9 arranged in shunt with the main and arcing contacts.

Upon opening of the circuit breaker due to pivotal counter-clockwise movement of the movable element 5 about a fixed shaft 14, separation of the main contacts 1 and 9 occurs prior to separation of the transfer andarci ng contacts for confining arcing and burning upon opening of the circuit to the latter contacts. The arc extinguishing means may comprise any suitable arrangement, as an arcing horn I5 connected to the stationary arcing contact 8 and a magnetic blowout coil 12 which is connected in series in the power circuit between the stationary arcing contact 8 and terminal l3.

The operative connection between the motor 3 and the thrust transmitting structure 4 comprises a rotatable shaft l1 directly connected to the motor 3, and a rotatable shaft I8 on which is mounted an actuating cam l9 coacting with the thrust transmitting structure 4. The motor shaft l1 and the cam shaft it are interconnected by automatic brake structure 20 and suitable speed reducing gearing 2|. Energization of the motor 3 efiects rotation of the actuating cam l9 and a circuit closing operation on the circuit breaker 2 through the thrust transmitting structure 4 in a manner hereinafter described.

In mechanism of this character it is highly desirable that over-running or over-travel of the actuating cam be prevented except within comis paratively narrow limits so that the operating mechanism may be readily tripped, reset and reclosed, if necessary, without interference by the actuating cam. Heretofore upon deenergization .of the motor the inertia of the moving parts made it very difflcult to control the final position of the actuating cam. The problem of mechanical braking is complicated by the fact that energization of the motor must be continued to a certain point to insure positive closing of the circuit breaker mediately upon deenergization in order that the actuating cam shall be stopped shortly beyond the point where the circuit closing operation is completed. I

For the purpose of braking the actuating cam immediately upon deenergization of the motor after the completion of the circuit closingoperation, the brake structure 20 is designed so that a brake member is moved to a non-braking position in response to predetermined motor torque and-is moved to a braking position in response to decrease of transmitted motor torque below said value. To this'end the motor shaft ii is connected to a brake member 22 by a resilient connection comprising a torsion spring 23 which is connected at one end as at 241 to the brake member 22 and at its other end as at'25 to the motor shaft 91. The shaft H likewise is provided with a limited lost motion connection with a hublike extension 22' of the brake member comprising a pin and slot connection 2t2l. I The brake member which comprises a disk or the like having an annular flange as illustrated for receiving the torsion spring 23 is provided with a centrally disposed recess 28 within which the lower end of the motor'shaft ll isfreely positioned. Accordingly, it will be noted that the brake member 22 may both rotate and move axially with respect to the motor shaft it within certain prescribedlimits.

The pin andslot connection 26-211 interconnecting the shaft Hand brake member .22 is arranged so that the pin 26, which is secured to the driving shaft ll, rides in a diagonal slot 21! in the hub member 22' so as to cam the brake member 22 in a direction axially of the shaft ll depending on the direction of rotation of said shaft. For the purpose of maintaining the brake member 22 in positive driving relation at all times to the driven shaft 29 which is directly connected to the actuating cam l9 through the reducing gearing 2|, the shaft 29 is provided with a squared extension 29' slidably mounted within a corresponding aperture in the lower end of the hub member 22'- Accordingly, the brake member 22 is always positively connected to the actuating cam notwithstanding axial movement of the brake member.

The actual braking surface of the brake member 22 may comprise any suitable brake lining material secured as at 38 to the lower side of the brake disk. A fixed brake member 80 comprising part of the 'brake housing surrounds the hub member 22' and-is provided with a brake surface 32 adapted to coact with the brake lining 8t.

The operation of the above-described brake structure is as follows. When the motor 3 is deenergized or at rest as illustrated in Fig. 2 the spring 23, which is normally under torsion, tends to rotate the brake member 22 with respect to the motor shaft H in the direction indicated so that the brake member 22 is cammed downwardly, through the pin and slot connection 25-27, to

engage the coacting fixed brake member 2i. The

spring 23 is designed so that it moves the brake member 22 to braking position when the torque transmitted by motor 3 decreases below a'certain value. Due to the fact that brake member 22 is positively connected to the shaft 29, it will be apparent that movement of the brake member 22 to its braking position efiects direct braking of the actuating cam as.

' Immediately upon energization of the, motor tending to rotate shaft ll in the direction indicated, referring more particularly to Fig. 3, the torsion of spring 23 isopposed by the motor torque. When the motortorque overcomes the torsion of spring 23, the spring yields permitting rotation of shaft I? with respect to brake mem ber 22. .After limited movement 'of the shaft H with respect to the brake member 22 the pin 26 engages the opposite end of the slot so as to constitute a direct and positive driving connection between shaft l'l, brake member 22 and shaft 29,

movement of the pin to this position in the meantime causing camming of the brake member 22 upwardly to a non-braking position as clearly illustrated in Fig. 3.

While the motor transmits normal torque through shaft ii the spring 23 is maintained flexed and under tension and the brake member is maintained in non-braking position. When, however, the motor is deenergized and the transmitted torque decreases to a certain value the opposingtorque of the charged spring 23 causes camming of the brake member 22 downwardly to the braking position illustrated in Fig. 2. Accordingly, there is provided a direct positive drive between the motor and actuating cam when the motor is transmitting the required torque, and likewise an automatic and quick acting brake effective in response to decrease of the motor torque upon completion of the circuit closing operation directly to brake the actuating cam.

The thrust transmitting structure 4 operatively interconnecting the actuating cam l9 and the movable circuit breaker element 5 is of the socalled trip-free type and is adapted to be reset and latched independently of the cam l9. Referring 'more particularly to Figs. 4, 5 and 6, the thrust pivotal support. The roller M -is arranged to be in the path of the actuating cam l9 when the circuit breaker is to be closed and the roller 22 is arranged to engage an inclined actuating face 413 of a pivoted supporting member 32 of the movable circuit breaker element 5. The member 22 which is pivotally mounted on shaft M1 is resiliently biased as by a compression spring 15 towards open circuit position.

'I'he'mechanism as illustrated by Fig. 4 is in the closed circuit position wherein the toggle 35-36 is overset so as to hold the element 5 in closed circuit position, the toggle being latched in this position by a pivoted latch member (is engaging the roller 2d. The latch 36} is provided with an extension 6t so as properly to position the latch with respect to. the roller an.

The toggle when latched as shown by Fig. 4 is maintained in an overset thrust-transmitting position by the fact that the reacting force of the circuit breaker is along the line of centers of pins 3'! and G2 and that this line is slightly offset with ei-aa' so that link as is m dead-center position with respect to the toggle thrust.

charged spring or the like for causing positive and quick release of the main latch 46. In other words, the available tripping force, which may be comparatively small as in the case of alternating current trip'coils, effects release of an intermediate energy-storing device as a spring charged trigger which in turn releases the main toggle controlling latch.

To this end the trip coil 50 coacts with a pivoted catch or latch 5i which is spring biased as at 52 so as normally to be engaged by a roller 53 carried by the trigger member 54. The trigger member 54, which is co-pivotally mounted at 55 with the latch 46, is resiliently biased as indicated at 56 in clockwise direction. The application of the spring tension at 56 is shown as slightly off-center with respect to the pivot 55 so that the spring force is available immediately to rotate the trigger member 54 clockwise upon releasing movement of catch 5|. A pin 66 carried by the trigger 54 is arranged so that upon clockwise movement of the trigger the pin sharply strikes an extension of the latch 46 so as to rotate the same clockwise to the toggle releasing position.

It will, therefore, be apparent that a much greater releasing force than that delivered by the trip coil 50 is available for releasing the latch 46 since the force required to maintain the spring 56 charged nearits dead-center position with respect to pivot 55 is obviously comparatively small.

- The resetting means for the latch and trigger arrangement above described is best illustrated by Figs. 5 and 6. The arrangement is such that immediately upon collapse of the main toggle -36 and circuit opening movement of the element 5, the trigger 54 is reset and the latch 46 positioned so that it is in readiness immediately to latch the main toggle when the roller 46 thereof returns to its initial position. The trigger resetting means may comprise any suitable arrangement as a member 58 carried. by the element 5 and provided with an extension 58 arranged to engage the trigger 54 and rotate the same counter-clockwise as illustrated in Fig. 5. 'Return of the trigger 54 to its initial position causes it to be latched by the catch 5| which is resiliently biased so that it snaps over the roller 53 as the same is rotated counter-clockwise. The resetting operation by the circuit breaker element 5 likewise recharges the spring at 56 by compressing the same against a fixed stop (not shown).

The positioning of the latch 46 for relatching the roller of the main toggle is accomplished by means of a resilient connection, as a leaf spring 59, arranged between the trigger 54 and latch 45. As illustrated, the spring 59 is secured at one end to the trigger 54 and is flexed so as to engage at its other end the latch 46 and urge the same in counter-clockwise direction. The stop pin 60 limits the counter-clockwise rotation of latch 46.

In order further to increase the sensitivity of the tripping means, the toggle member 35 in riding under the latch 46 to its latched position may flex the spring 59 sufiiciently so that the trigger spring at 56 is on dead center with respect to pivot 55. In this arrangement the tension of spring 59 is sufiicient, upon releasing movement of catch 5!, to move the trigger 54 clockwise ofi center so that the trigger is immediately snapped over to actuate the latch 46.

Immediately after collapse of toggle 3536 and opening movement of the element 5, the toggle member 35 is urged counter-clockwise from the position shown in Fig. 5 by a spring 6| until the extension 39 engages a stop 39. When the toggle member 35 is returned to this position the latch 46 snaps over the roller 40 as illustrated by Fig. 6. In this position the toggle member 36 may berotated counter-clockwise about the restrained pivot 31 by the actuating cam I 5 so that the roller 42 in riding along the inclined face 43 causes circuit closing movement of the element 5. The cam l9, which rotates clockwise to engage the roller' i4, is designed to meet the operating characteristics of the circuit breaker so that the same may always be positively closed without difficulty. The brake mechanism above described is efiective to stop rotation of cam l9 within a few degrees of rotation after circuit closing movement of the main toggle as illustrated in Fig. 4. The cam in this position is, therefore, free of the thrust transmitting structure and is likewise in a predetermined position for efiecting a circuit closing operation by a single revolution thereof.

A modified form of the resetting device for the trigger 54 is illustrated by Fig. 9. In this arrangement the trigger 54 is returned to its latched position notwithstanding limited variations in the final open circuit position of the element 5. The element 5 which is biased by spring against the stop member 5' may, due to friction of the apparatus and other causes, come to rest short of the stop member. In the arrangement shown in Fig. 9, an intermediate member 62 pivotally supported at 63 is adapted to be engaged by a buffer member 64 of the element 5. The member 62 is thereby swung clockwise into engagement with the trigger 54 resetting the same in the manner above described. In the present case, however, the final movement of the element 5 efiects comparatively small movement of the trigger 54 due to the lengthening of the lever arm with respect to pivot 63. Accordingly, the trigger 54 may be reset during the main part of the opening travel of the element 5, thetrigger being unaffected by slight variations in the final position of said element.

In summarizing the operation of the mechanism, it may be briefiy stated that the thrust transmitting toggle 3536 is held in a thrust transmitting position, both in the closed circuit position illustrated by Fig. 4 and also during rotation of the toggle member 36 by the actuating cam is, by the latch 46 which is in turn controlled by the spring charged trigger 54. The trigger is nicely balanced so that a comparatively small trip force is effective to actuate the same. actuates the catch 5! causing release of trigger 54 and consequent actuation of latch 46 with the result that the toggle 35--36 is no longer restrained in thrust transmitting position and collapses under the action of the circuit breaker opening spring 45 as illustrated by Fig. 5. Im-

mediately upon opening, however, the element 5 through the resetting means above described resets the spring charged trigger 54 which in turn through spring 59 positions the latch 46 for re- The tripping impulse at the trip coil setting so that the lower edge thereof is in the path of the toggle roller 66.

After collapse of the toggle 35-36 and opening of the circuit breaker, the toggle spring 6i throws the toggle from the position shown in Fig. 5 to that shown in Fig. 6 wherein the roller 30 engages the restraining face of latch 56. The mechanism is now in readiness for a closing operation which is accomplished by a single clockwise revolution of the actuating cam i9, returning the mechanism to the position illustrated in Fig. 4.

.It will be noted that the mechanism is tripfree at all stages of its operation. That is, the occurrence of a tripping impulse during the camming operation causes actuation of the latch 46 in the usual manner and collapse of the toggle 35-36, the element 5 thereupon returning to open circuit position notwithstanding continued rotation of the cam Hi. When the cam comes to rest the toggle spring 6! causes relatching of the toggle in the manner above described.

Where manual operation of. the circuit breaker, either alone or in combination with the motor, is desired, an actuating cam 65 (Fig. 1) similar in design to cam I9 is mounted on a shaft 66'so as likewise to coact with the toggle roller M. In the present instance the shaft 66, which is provided with an operating handle 61 at the outer end thereof, extends longitudinally through the hollow motor operated cam shaft I 8 so that the handle 6! may be applied to the opposite end of the shaft where necessary. The operation of shafts l8 and 66 are entirely independentof each other.

The shaft 66 is provided with a tripping and positioning member 68 arranged to engage, as by extension 68, a guided member 69 coacting with the extension 46 of the maintoggle latch. When tripping of. the breaker by the manual means is desired the handle 61 is rotated counter-clock-" wise (as viewed in Fig. 1) a short distance so that the member 69 is raised and the latch 46 actuated to release the toggle 35-36. A positioning spring 16 coacting with notches in the member 68 serves to maintain the shaft 66 in definite positions.

In Fig. 1 there is likewise illustrated a. control system for insuring proper operation of the motor. The motor as shown is energized from a suitable source of power, indicated at H, the motor control circuit including a push button control switch 12, circuit breaker limit switch 13, a

and manual control switch I4. When the manual operating means is in inoperative position and the element 5 of the circuit breaker is in open circuit position the manual switch 36 and the limit switch 13 are both closed. An interconnecting linkage l5 serves to operate the limit switch 13 in accordance with opening and closing movements of element 5.

The control circuit which includes a solenoid 16 may be completed by closing of the push button switch 12. Energization of solenoid i6 is in turn effective to close contacts Ti thereby completing the motor circuit through the manual switch Hi. Shortly after closing of contacts Ti and energization of. the motor, the push button lZmay be released since the plunger of solenoid i6 is mechanically sealed in contacting position by a cam element 78 mounted on shaft 88. The

cam 18 seals in the contacts Ti only during normal travel of cam l 9, the motor meanwhile being energized from the source H directly through contacts 11 and switch 16. Upon completion of th circuit closing operation the cam it permits the contacts 71 to be biased open thereby deenergizing the motor and stopping the actuating cam 59.

When the switch element 5 is closed the limit switch 13 is open preventing energization of solenoid 16 from source 11 through push button I2. In the case of trip-free operation the actuating cam I9 is rotated to its normal final position due to the sealing-in cam 18. When the manually operated cam is rotated to operative position, the switch 14 is opened with the result that energization of the motor 3 from the source H is impossible.

The present invention is not limited to the specific type of. circuit breaker shown, it being understood that the movable element 5 is equivalent to the movable element generally of a circuit breaker of either the air or oil type. The more detailed construction of the air circuit breaker illustrated is as follows:

As previously described the movable contacts of the circuit breaker are carried by the element 5 which includes the pivoted arm 44 on which is mounted an insulating cross-bar 80. Secured to the cross-bar are a plurality of contact supporting members 8|, each member being channelshaped as illustrated and -forming a bearing at 82 for the pivot pin of an arcing contact support 83. Each contact support 83 is resiliently biased, as by springs 84, clockwise so as normally to urge the corresponding arcing contact point into engagement with its coacting contact. This movement is limited by a pin 85 adapted to engage a leg 85 forming a part of the member 8|. The main current-carrying contacts 1 are mounted within the supports 8| for limited reciprocal movement, as by pin and slot connection 86-86. The contacts I are biased by a spring 81 so as to provide resilient engagement of the contacts I and 9.

The transfer contacts I are connected to the corresponding contacts I by a flux conducting strip 88. Upon opening of the circuit, current through the main contacts 'i and 9 is first trans ferred to the contacts I and 9 in order to avoid burning at the main contacts. Heavy currents cannot be shunted directly to the arcing coils without some burning at the main contacts by reason of the inductance of the blowout coil.

The above described circuit breaker and operating mechanism are compactly assembled and designed so that each main component part may be assembled or disassembled as a unit with respect to the associated parts. In the present instance the motor 3 and brake structure 22 is assembled as a unit with respect to the shaft 29 by simply positioning the motor and brake unit above the shaft and sliding the hub 22' on the squared extension 29' of the shaft. The reduc ing gearing 2| and a portion of the shaft l8 are likewise removable as a unit by reason of a detachable interlocked connection dividing the shaft I8 into separate sections as indicated at 90. Upon disassembly, the reducing gearing and associated portion of shaft l8 are slidable longitudinally ofi the manually operated shaft 66 after removal of the motor and brake unit.

- In view of the fact that the thrust transmitting structure t has no permanent connection with the movable element 5, it will be apparent that this portion of the structure including the actuating cam and the corresponding section of the cam shaft may be constructed and assembled as a unit with respect to the remainder of the mechanism. The same likewise applies to the latch and trigger mechanism. A mechanism so designed is not only 'quickly and efliciently assembled but may be produced at comparatively low cost. That is, the component units may be individually constructed so that considerable time is saved as compared with the usual method of having a number oi! workmen assemble the entire apparatus in a single frame.

The complete circuit breaker and mechanism unit are illustrated by Figs! and 8 wherein a panel 9| has mounted thereon the phase units of the circuit breaker 2 and the operating mechanism-therefor including the motor and brake unit indicated at 92, the reduction gearing unit indicated at 93 and the thrust transmitting and tripping and latching units indicated at 94 and 95, respectively. An auxiliary switch unit including the limit switch is indicated at 96. Starting with the motor and brake unit, the mechanism may be readily disassembled by units by merely loosening and removing the clamping bolts provided for securing together the casings of said units where indicated.

It should be understood that my invention is not limited to specific details of construction and arrangement thereof herein illustrated, and that changes and modifications may occur to one skilled in the art without departing from the spirit of my invention.

What I claim as new and desire to secure by Letters Patent 01 the United States is:

1. Operating mechanism of the trip-free type for electric circuit breakers comprising a link having a fixed pivot, said link having a portion coacting with tripping means for restraining said link, a second link carried by and pivotally mounted on said first-named link, said second link operatively connected at one portion to the movable element of a circuit breaker, and actuating means adapted to engage another portion of said second link for rotating the same about its pivotal mounting on said first-named link so as to effect circuit closing movement of said movable element, said second link in said closed circuit position assuming a dead center position with respect to the reacting force of said movable element.

2. Operating mechanism of the trip-free type for electric circuit breakers, comprising a link having a fixed pivot, said link having a portion coacting with tripping means for restraining said link, a second link carried by and pivotally mounted on said first-named link, said second link provided with a roller arranged to engage an inclined surface of the movable element of the circuit breaker, and actuating means adapted to engage another portion of said second link for rotating the same so that said movable element is cammed by said roller to closed circuit position, the reacting force of said movable element being in deadcenter relation to said second link and tending to rotate said first link in opposition to the restraint of said tripping means in said closed circuit position.

3. Operating mechanism of the trip-free type for electric circuit breakers comprising a link having a fixed pivot, said link having a portion coacting with tripping means for restraining said link, a second link carried by and pivotally mounted on said first-named link, said second link provided with a roller arranged to engage an inclined surface of the movable element of the circuit breaker, actuating means adapted to engage another portion of said second link for rotating the same so that said movable element is cammed by said roller to closed circuit position, and a prop arranged to maintain said roller in said position against accidental release.

4. Operating mechanism-oi. the trip-free type comprising collapsible thrust transmitting structure, a latch for restraining said structure in thrust transmitting position, a coacting trigger member movable independently of said latch and resiliently biased towards a latch releasing position, means latching said trigger member, release of said trigger member causing in turn release of said latch and collapse of said thrust transmitting structure to open position, means effecting resetting of said trigger member in response to opening movement of said structure, and a resilient connection between said trigger member and latch eflecting in turn resetting of said latch with respect to said thrust transmitting structure.

5. Operating mechanism of the trip-free type for electric circuit breakers comprising collapsible thrust transmitting structure arranged to effect circuit closing movement of the movable element of the circuit breaker, a latch for restraining said structure in thrust transmitting position, a coacting pivoted trigger member movable independently of said latch and resiliently biased towards latch releasing position, means latching said trigger member, release of said latching means causing in turn rotation of said trigger member to latch releasing position, collapse of said thrust transmitting structure and opening movement of said circuit breaker element, means carried by said element for rotating said trigger member back to its latched position during the opening movement of said element, and a spring connection between said trigger member and latch for returning said latch to its latched position with respect to said thrust transmitting structure.

LEONARD J, LINDE.

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